// http://gladman.plushost.co.uk/oldsite/AES/index.php

#include <stdint.h>

#include "aes.h"

#define BPOLY 0x1B
#define DPOLY 0x8D

const uint8_t sbox[256] = {
    0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76,
    0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0, 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0,
    0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, 0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15,
    0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a, 0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75,
    0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0, 0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84,
    0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b, 0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf,
    0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85, 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8,
    0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, 0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2,
    0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17, 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73,
    0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, 0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb,
    0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c, 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79,
    0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9, 0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08,
    0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6, 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a,
    0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, 0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e,
    0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94, 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf,
    0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16
};

const uint8_t isbox[256] = {
    0x52, 0x09, 0x6a, 0xd5, 0x30, 0x36, 0xa5, 0x38, 0xbf, 0x40, 0xa3, 0x9e, 0x81, 0xf3, 0xd7, 0xfb,
    0x7c, 0xe3, 0x39, 0x82, 0x9b, 0x2f, 0xff, 0x87, 0x34, 0x8e, 0x43, 0x44, 0xc4, 0xde, 0xe9, 0xcb,
    0x54, 0x7b, 0x94, 0x32, 0xa6, 0xc2, 0x23, 0x3d, 0xee, 0x4c, 0x95, 0x0b, 0x42, 0xfa, 0xc3, 0x4e,
    0x08, 0x2e, 0xa1, 0x66, 0x28, 0xd9, 0x24, 0xb2, 0x76, 0x5b, 0xa2, 0x49, 0x6d, 0x8b, 0xd1, 0x25,
    0x72, 0xf8, 0xf6, 0x64, 0x86, 0x68, 0x98, 0x16, 0xd4, 0xa4, 0x5c, 0xcc, 0x5d, 0x65, 0xb6, 0x92,
    0x6c, 0x70, 0x48, 0x50, 0xfd, 0xed, 0xb9, 0xda, 0x5e, 0x15, 0x46, 0x57, 0xa7, 0x8d, 0x9d, 0x84,
    0x90, 0xd8, 0xab, 0x00, 0x8c, 0xbc, 0xd3, 0x0a, 0xf7, 0xe4, 0x58, 0x05, 0xb8, 0xb3, 0x45, 0x06,
    0xd0, 0x2c, 0x1e, 0x8f, 0xca, 0x3f, 0x0f, 0x02, 0xc1, 0xaf, 0xbd, 0x03, 0x01, 0x13, 0x8a, 0x6b,
    0x3a, 0x91, 0x11, 0x41, 0x4f, 0x67, 0xdc, 0xea, 0x97, 0xf2, 0xcf, 0xce, 0xf0, 0xb4, 0xe6, 0x73,
    0x96, 0xac, 0x74, 0x22, 0xe7, 0xad, 0x35, 0x85, 0xe2, 0xf9, 0x37, 0xe8, 0x1c, 0x75, 0xdf, 0x6e,
    0x47, 0xf1, 0x1a, 0x71, 0x1d, 0x29, 0xc5, 0x89, 0x6f, 0xb7, 0x62, 0x0e, 0xaa, 0x18, 0xbe, 0x1b,
    0xfc, 0x56, 0x3e, 0x4b, 0xc6, 0xd2, 0x79, 0x20, 0x9a, 0xdb, 0xc0, 0xfe, 0x78, 0xcd, 0x5a, 0xf4,
    0x1f, 0xdd, 0xa8, 0x33, 0x88, 0x07, 0xc7, 0x31, 0xb1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xec, 0x5f,
    0x60, 0x51, 0x7f, 0xa9, 0x19, 0xb5, 0x4a, 0x0d, 0x2d, 0xe5, 0x7a, 0x9f, 0x93, 0xc9, 0x9c, 0xef,
    0xa0, 0xe0, 0x3b, 0x4d, 0xae, 0x2a, 0xf5, 0xb0, 0xc8, 0xeb, 0xbb, 0x3c, 0x83, 0x53, 0x99, 0x61,
    0x17, 0x2b, 0x04, 0x7e, 0xba, 0x77, 0xd6, 0x26, 0xe1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0c, 0x7d
};

// #define xtime(x)	( (x << 1) ^ (((x >> 7) & 1) * BPOLY) )
// #define xtime(x)	( (x << 1) ^ ((x & 0x80) ? BPOLY : 0) )

const uint8_t xtime[256] = {
    0x00, 0x02, 0x04, 0x06, 0x08, 0x0a, 0x0c, 0x0e, 0x10, 0x12, 0x14, 0x16, 0x18, 0x1a, 0x1c, 0x1e,
    0x20, 0x22, 0x24, 0x26, 0x28, 0x2a, 0x2c, 0x2e, 0x30, 0x32, 0x34, 0x36, 0x38, 0x3a, 0x3c, 0x3e,
    0x40, 0x42, 0x44, 0x46, 0x48, 0x4a, 0x4c, 0x4e, 0x50, 0x52, 0x54, 0x56, 0x58, 0x5a, 0x5c, 0x5e,
    0x60, 0x62, 0x64, 0x66, 0x68, 0x6a, 0x6c, 0x6e, 0x70, 0x72, 0x74, 0x76, 0x78, 0x7a, 0x7c, 0x7e,
    0x80, 0x82, 0x84, 0x86, 0x88, 0x8a, 0x8c, 0x8e, 0x90, 0x92, 0x94, 0x96, 0x98, 0x9a, 0x9c, 0x9e,
    0xa0, 0xa2, 0xa4, 0xa6, 0xa8, 0xaa, 0xac, 0xae, 0xb0, 0xb2, 0xb4, 0xb6, 0xb8, 0xba, 0xbc, 0xbe,
    0xc0, 0xc2, 0xc4, 0xc6, 0xc8, 0xca, 0xcc, 0xce, 0xd0, 0xd2, 0xd4, 0xd6, 0xd8, 0xda, 0xdc, 0xde,
    0xe0, 0xe2, 0xe4, 0xe6, 0xe8, 0xea, 0xec, 0xee, 0xf0, 0xf2, 0xf4, 0xf6, 0xf8, 0xfa, 0xfc, 0xfe,
    0x1b, 0x19, 0x1f, 0x1d, 0x13, 0x11, 0x17, 0x15, 0x0b, 0x09, 0x0f, 0x0d, 0x03, 0x01, 0x07, 0x05,
    0x3b, 0x39, 0x3f, 0x3d, 0x33, 0x31, 0x37, 0x35, 0x2b, 0x29, 0x2f, 0x2d, 0x23, 0x21, 0x27, 0x25,
    0x5b, 0x59, 0x5f, 0x5d, 0x53, 0x51, 0x57, 0x55, 0x4b, 0x49, 0x4f, 0x4d, 0x43, 0x41, 0x47, 0x45,
    0x7b, 0x79, 0x7f, 0x7d, 0x73, 0x71, 0x77, 0x75, 0x6b, 0x69, 0x6f, 0x6d, 0x63, 0x61, 0x67, 0x65,
    0x9b, 0x99, 0x9f, 0x9d, 0x93, 0x91, 0x97, 0x95, 0x8b, 0x89, 0x8f, 0x8d, 0x83, 0x81, 0x87, 0x85,
    0xbb, 0xb9, 0xbf, 0xbd, 0xb3, 0xb1, 0xb7, 0xb5, 0xab, 0xa9, 0xaf, 0xad, 0xa3, 0xa1, 0xa7, 0xa5,
    0xdb, 0xd9, 0xdf, 0xdd, 0xd3, 0xd1, 0xd7, 0xd5, 0xcb, 0xc9, 0xcf, 0xcd, 0xc3, 0xc1, 0xc7, 0xc5,
    0xfb, 0xf9, 0xff, 0xfd, 0xf3, 0xf1, 0xf7, 0xf5, 0xeb, 0xe9, 0xef, 0xed, 0xe3, 0xe1, 0xe7, 0xe5
};

// ***********************************************************************************
/*
   void createXTimeTable(void)
   {
        uint8_t i = 0;
        do {
                xtime[i] = (i << 1) ^ ((i & 0x80) ? BPOLY : 0);
        } while (++i != 0);
   }
 */
// ***********************************************************************************
/*
   uint8_t powTable[256];
   uint8_t logTable[256];

   uint8_t sbox[256];
   uint8_t isbox[256];

   void createPowLogTables(void)
   {
        uint8_t i = 0;
        uint8_t t = 1;

        do {
                powTable[i] = t;
                logTable[t] = i;
                i++;
                t ^= (t << 1) ^ ((t & 0x80) ? BPOLY : 0);
        } while (t != 1);

        powTable[255] = powTable[0];
   }

   void createSubstitueBoxTable(void)
   {
        int i = 0;
        do {
                uint8_t temp;

                if (i > 0)
                        temp = powTable[255 - logTable[i]];
                else
                        temp = 0;

                uint8_t sb = temp ^ 0x63;
                for (int j = 0; j < 4; j++)
                {
                        temp = (temp << 1) | (temp >> 7);
                        sb ^= temp;
                }

                sbox[i] = sb;
        } while (++i != 0);
   }

   void createInverseSubstitueBoxTable(void)
   {
        uint8_t i = 0;
        uint8_t j = 0;
        do {
                do {
                        if (sbox[j] == i)
                        {
                                isbox[i] = j;
                                j = 255;
                        }
                } while (++j != 0);
        } while (++i != 0);
   }
 */
// ***********************************************************************************

void copy_block(void *d, void *s)
{
    if (d == s) {
        return;
    }

    register uint8_t *src  = s;
    register uint8_t *dest = d;
    for (int i = N_BLOCK; i; --i) {
        *dest++ = *src++;
    }
}

void xor_block(void *d, void *s)
{
    register uint8_t *src  = s;
    register uint8_t *dest = d;

    for (int i = N_BLOCK; i; --i) {
        *dest++ ^= *src++;
    }
}

void xor_word(uint8_t *d, uint8_t *s)
{
    *d++ ^= *s++;
    *d++ ^= *s++;
    *d++ ^= *s++;
    *d++ ^= *s++;
}

void xor_sub_word(uint8_t *d, uint8_t *s)
{
    *d++ ^= sbox[*s++];
    *d++ ^= sbox[*s++];
    *d++ ^= sbox[*s++];
    *d++ ^= sbox[*s++];
}

void xor_sub_rot_word(uint8_t *d, uint8_t *s, uint8_t rc)
{
    *d++ ^= sbox[s[1]] ^ rc;
    *d++ ^= sbox[s[2]];
    *d++ ^= sbox[s[3]];
    *d++ ^= sbox[s[0]];
}

void mix_sub_column(uint8_t *a)
{
    uint8_t a0  = a[0];
    uint8_t a1  = a[1];
    uint8_t a2  = a[2];
    uint8_t a3  = a[3];
    uint8_t tmp = a0 ^ a1 ^ a2 ^ a3;

    a[0] = a0 ^ xtime[a0 ^ a1] ^ tmp;
    a[1] = a1 ^ xtime[a1 ^ a2] ^ tmp;
    a[2] = a2 ^ xtime[a2 ^ a3] ^ tmp;
    a[3] = a3 ^ xtime[a3 ^ a0] ^ tmp;
}

void mix_sub_columns(void *a)
{
    mix_sub_column((uint8_t *)a + 0);
    mix_sub_column((uint8_t *)a + 4);
    mix_sub_column((uint8_t *)a + 8);
    mix_sub_column((uint8_t *)a + 12);
}

void inv_mix_sub_column(uint8_t *a)
{
    uint8_t tmp;

    tmp   = xtime[xtime[a[0] ^ a[2]]];
    a[0] ^= tmp;
    a[2] ^= tmp;
    tmp   = xtime[xtime[a[1] ^ a[3]]];
    a[1] ^= tmp;
    a[3] ^= tmp;
}

void inv_mix_sub_columns(void *a)
{
    inv_mix_sub_column((uint8_t *)a + 0);
    inv_mix_sub_column((uint8_t *)a + 4);
    inv_mix_sub_column((uint8_t *)a + 8);
    inv_mix_sub_column((uint8_t *)a + 12);

    mix_sub_columns(a);
}

void shift_sub_rows(uint8_t *a)
{
    uint8_t tmp;

    a[0]  = sbox[a[0]];
    a[4]  = sbox[a[4]];
    a[8]  = sbox[a[8]];
    a[12] = sbox[a[12]];

    tmp   = a[1];
    a[1]  = sbox[a[5]];
    a[5]  = sbox[a[9]];
    a[9]  = sbox[a[13]];
    a[13] = sbox[tmp];

    tmp   = a[2];
    a[2]  = sbox[a[10]];
    a[10] = sbox[tmp];
    tmp   = a[6];
    a[6]  = sbox[a[14]];
    a[14] = sbox[tmp];

    tmp   = a[15];
    a[15] = sbox[a[11]];
    a[11] = sbox[a[7]];
    a[7]  = sbox[a[3]];
    a[3]  = sbox[tmp];
}

void inv_shift_sub_rows(uint8_t *a)
{
    uint8_t tmp;

    a[0]  = isbox[a[0]];
    a[4]  = isbox[a[4]];
    a[8]  = isbox[a[8]];
    a[12] = isbox[a[12]];

    tmp   = a[13];
    a[13] = isbox[a[9]];
    a[9]  = isbox[a[5]];
    a[5]  = isbox[a[1]];
    a[1]  = isbox[tmp];

    tmp   = a[2];
    a[2]  = isbox[a[10]];
    a[10] = isbox[tmp];
    tmp   = a[6];
    a[6]  = isbox[a[14]];
    a[14] = isbox[tmp];

    tmp   = a[3];
    a[3]  = isbox[a[7]];
    a[7]  = isbox[a[11]];
    a[11] = isbox[a[15]];
    a[15] = isbox[tmp];
}

// ***********************************************************************************

// 'on the fly' encryption key update for 128 bit keys
void update_encrypt_key_128(uint8_t *k, uint8_t *rc)
{
    xor_sub_rot_word(k + 0, k + 12, *rc);

    *rc = (*rc << 1) ^ ((*rc & 0x80) ? BPOLY : 0);

    for (int i = 4; i < 16; i += 4) {
        xor_word(k + i + 0, k + i - 4);
    }
}

// Encrypt a single block of 16 bytes
void aes_encrypt_cbc_128(void *data, void *key, void *chain_block)
{
    uint8_t rc = 1;

    if (chain_block) {
        xor_block(data, chain_block);
    }

    for (int round = 10; round; --round) {
        xor_block(data, key); // add_round_key
        update_encrypt_key_128((uint8_t *)key, &rc);
        shift_sub_rows(data);
        if (round <= 1) {
            continue;
        }
        mix_sub_columns(data);
    }
    xor_block(data, key); // add_round_key

    if (chain_block) {
        copy_block(chain_block, data);
    }
}

// 'on the fly' decryption key update for 128 bit keys
void update_decrypt_key_128(uint8_t *k, uint8_t *rc)
{
    for (int i = 12; i; i -= 4) {
        xor_word(k + i + 0, k + i - 4);
    }

    *rc = (*rc >> 1) ^ ((*rc & 1) ? DPOLY : 0);

    xor_sub_rot_word(k + 0, k + 12, *rc);
}

// Decrypt a single block of 16 bytes
void aes_decrypt_cbc_128(void *data, void *key, void *chain_block)
{
    uint8_t tmp_data[N_BLOCK];

    uint8_t rc = 0x6c;

    copy_block(tmp_data, data);

    xor_block(data, key); // add_round_key
    for (int round = 10; round; --round) {
        inv_shift_sub_rows(data);
        update_decrypt_key_128(key, &rc);
        xor_block(data, key); // add_round_key
        if (round <= 1) {
            continue;
        }
        inv_mix_sub_columns(data);
    }

    if (chain_block) {
        xor_block(data, chain_block);
        copy_block(chain_block, tmp_data);
    }
}

void aes_decrypt_key_128_create(void *enc_key, void *dec_key)
{
    copy_block(dec_key, enc_key);

    uint8_t rc = 1;
    for (int i = 0; i < 10; i++) {
        update_encrypt_key_128(dec_key, &rc);
    }
}

// ***********************************************************************************

// 'on the fly' encryption key update for 256 bit keys
void update_encrypt_key_256(uint8_t *k, uint8_t *rc)
{
    xor_sub_rot_word(k + 0, k + 28, *rc);

    *rc = (*rc << 1) ^ ((*rc & 0x80) ? BPOLY : 0);

    for (int i = 4; i < 16; i += 4) {
        xor_word(k + i + 0, k + i - 4);
    }

    xor_sub_word(k + 16, k + 12);

    for (int i = 20; i < 32; i += 4) {
        xor_word(k + i + 0, k + i - 4);
    }
}

// Encrypt a single block of 16 bytes
void aes_encrypt_cbc_256(void *data, void *key, void *chain_block)
{
    uint8_t rc = 1;

    if (chain_block) {
        xor_block(data, chain_block);
    }

    for (int round = 7; round; --round) {
// printf("key - ");
// uint8_t *p = key;
// for (int i = 0; i < 32; i++) printf("%0.2X ", *p++);
// printf("\r\n");

        xor_block(data, key); // add_round_key
        shift_sub_rows(data);
        mix_sub_columns(data);
        xor_block(data, (uint8_t *)key + 16); // add_round_key
        update_encrypt_key_256(key, &rc);
        shift_sub_rows(data);
        if (round <= 1) {
            continue;
        }
        mix_sub_columns(data);
    }
    xor_block(data, key); // add_round_key

    if (chain_block) {
        copy_block(chain_block, data);
    }
}

// 'on the fly' decryption key update for 256 bit keys
void update_decrypt_key_256(uint8_t *k, uint8_t *rc)
{
    for (int i = 28; i >= 20; i -= 4) {
        xor_word(k + i + 0, k + i - 4);
    }

    xor_sub_word(k + 16, k + 12);

    for (int i = 12; i; i -= 4) {
        xor_word(k + i + 0, k + i - 4);
    }

    *rc = (*rc >> 1) ^ ((*rc & 1) ? DPOLY : 0);

    xor_sub_rot_word(k + 0, k + 28, *rc);
}

// Decrypt a single block of 16 bytes
void aes_decrypt_cbc_256(void *data, void *key, void *chain_block)
{
    uint8_t tmp_data[N_BLOCK];

    uint8_t rc = 0x80;

    copy_block(tmp_data, data);

    xor_block(data, key); // add_round_key
    for (int round = 7; round; --round) {
        inv_shift_sub_rows(data);
        update_decrypt_key_256(key, &rc);
        xor_block(data, (uint8_t *)key + 16); // add_round_key
        inv_mix_sub_columns(data);
        inv_shift_sub_rows(data);
        xor_block(data, key); // add_round_key
        if (round <= 1) {
            continue;
        }
        inv_mix_sub_columns(data);
    }

    if (chain_block) {
        xor_block(data, chain_block);
        copy_block(chain_block, tmp_data);
    }
}

void aes_decrypt_key_256_create(void *enc_key, void *dec_key)
{
    if (dec_key != enc_key) {
        copy_block(dec_key, enc_key);
        copy_block((uint8_t *)dec_key + 16, (uint8_t *)enc_key + 16);
    }

    uint8_t rc = 1;
    for (int i = 7; i; --i) {
        update_encrypt_key_256(dec_key, &rc);
    }
}

// ***********************************************************************************
